1. Field of the Invention
This application is directed to wall structures and methods of making wall structures to provide protection against uplift of the wall structures during hurricanes, tornadoes and other high wind conditions.
2. Description of the Related Art
During high winds caused by hurricanes, tornadoes and other extreme weather conditions, one common failure mode of homes and other structures is that the building is lifted from the foundation and then displaced and effectively destroyed. Generally, a structure relies primarily on gravity to maintain the structure on a foundation, such as, for example, a concrete slab, a concrete footing or the like, which is embedded in the ground. The walls of a conventional structure may be anchored to the foundation by a number of hold-down bolts embedded in the concrete and bolted to the mudsill at the base of the wall. One or more of the vertical studs in a wall section may also be bolted to the foundation using hold-down systems such as, for example, the systems described in U.S. Pat. Nos. 4,825,621, 5,388,804, 5,535,561, 6,560,940.
One common issue with the installation of the hold-down bolts and similar systems for anchoring the walls of a structure to a foundation is the cost of the parts and labor required to accomplish the installation and also the need to install the embedded bolt in the concrete when the concrete is poured. In particular, the position of each bolt must be designated in advance, and the bolt must be maintained in a vertical orientation at the designated position until the concrete sets. Then, when the framing of the structure is erected, holes must be formed in the mudsill at the correct locations so that the bolts pass through the mudsill. If the bolts are fastened to vertical studs, the positioning of the bolts must be more precise in order to be disposed alongside the studs.
Because of the costs for the parts and labor, many structures, such as private homes do not include enough hold-down bolts to restrain the structures during high wind conditions. Even if a sufficient number of hold-down bolts are included, only the mudsill or the selected vertical studs are physically connected to the foundation. Thus, when the wind reaches a sufficient intensity or when the wind achieves a resonant condition with the structure, lateral movement of the wall may cause portions of the wall to tear away from the foundation.